On large livestock farms, holdings of animal stock are typically maintained within stables or animal confinement buildings. The animals and animal waste inside the buildings generate offensive odors which travel via airborne particles and gases. The odors are typically vented to the outside atmosphere and result in unpleasant conditions for people who live or work in or around the buildings. In particular, such odors are a frequent cause of concern and complaint from neighboring inhabitants. In addition, rising environmental awareness and concerns place increasing pressure on farmers to reduce or eliminate atmospheric pollutants produced by large holdings of livestock. It would be desirable to provide apparatus and methods for eliminating odors from the air exhaust of animal confinement buildings.
Methods to treat atmospheric pollutants in industrial exhaust air are known. One such method is gas-washing, which typically includes the use of washing water treated with lyes, alkalis or phosphates to remove the odor-carrying agents in the air exhaust. Such methods have limited use because the water effluent produced is itself a source of environmental pollution. It would be desirable to provide environmentally sound apparatus and methods for eliminating odors from the air exhaust of animal confinement buildings.
Known methods for removing particles from air exhaust which avoid the use of lyes, alkalis or phosphates include the use of wet-scrubbers. Some of these methods employ the addition of biodegradable, environmentally sound compounds such as partial esters of alcohols or ampholytic compounds. Wet-scrubbers typically employ exchange elements having extensive and complex washing water/air interfaces to facilitate the removal of particulates from the air into the water, and some require heat exchangers and cooling media. The exchange elements used with such methods are expensive to fabricate, expensive to purchase, and also require high energy input to generate turbulence for creating water-air contact. These costs represent a disadvantage for farmers or others who desire methods and apparatus for use on a commercial scale.
Methods and apparatus which employ biological or active carbon filters for removing odors and particles from air exhaust are known. Such methods avoid or limit the production of environmental pollutants and are relatively simple in design. However, filters are also typically expensive to purchase and maintain, and are characterized by high air flow resistance, which make them impractical for use on a commercial scale. It would be desirable to provide apparatus and methods for removing odor from animal confinement buildings which are simple in design, simple to implement, inexpensive to purchase, and have a low energy cost.